Synthesis and application of hydrochar from artichoke as an innovative product to increase soil fertility and act as plant biostimulant

Soil degradation, which is mostly due to human over-exploitation and climate change, severely impacts on global food production and terrestrial biodiversity. The hydrochar (HC) is an innovative and still unexplored product, resulting from the hydrothermal carbonization of organic biomass, and potentially acting as improver of soil fertility. Therefore, artichoke biomass was processed with subcritical water to produce several HC lines which were investigated as both ameliorative of soil quality and plant biostimulant. HCs were developed adopting two temperature and pressure conditions (180°C and 10 Bar; 215°C and 20 Bar) and evaluating different types of artichoke wastes (stems and bracts, either alone or combined in a ratio 30:70 w/w and viceversa ). Solid hydrochars (HC_sol) showed good levels of nitrogen (5-14 g/kg) and ash (1.3-6%), along with strong waterholding capacity. HC_sol also exhibited the ability to adsorb heavy metals (cadmium and lead) thus paving the way to environmental applications, The liquid phases (HC_liq) showed an acidic pH (3.5-4) and high levels of phosphorous and phenols serving as plant biostimulants. When applied at the proper concentrations, several lines of HC_liq exerted an efficient biostimulant action on cress and radish seeds, up to elicit a response 55% higher than the control. For cress, the best HC-liq was that obtained by 100% stems at 215°C, while, for radish, the more efficient HC_liqs were those achieved by 70% bracts at 215°C and 100% stems at 180°C. Our outcomes proved that HC is a virtuous, green and promising technique to recycle artichoke wastes. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany